# EMIS 2022 at RAON

Asia/Seoul
S236 (Science Culture Center, IBS)

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
,
Description

The 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS) will be held at the Science Culture Center of IBS in Daejeon, South Korea, from October 3 to 7, 2022.

Scientific topics of EMIS 2022 include:

• Isotope production, target, and ion source techniques
• Techniques related to high-power radioactive ion beam production
• Low-energy and in-flight separators
• Storage rings
• Ion guide, gas catcher, and beam manipulation techniques
• Ion optics and spectrometers
• Ion traps and laser techniques
• Instrumentation for radioactive ion beam experiments
• Applications of radioactive ion beams

This meeting will be sponsored with the help of the kind cooperative organizations:

- Student travel support for EMIS 2022 will be partially provided by A3-Foresight Program of NRF

Contact
• Monday, October 3
• Introduction S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Session 1
• 1
The SCRIT electron scattering facility at the RIKEN RI Beam Factory

Electron scattering is a powerful tool for studying nuclear structure, and it has been long-awaited for unstable nuclei, because it allows model-independent studies of nuclear structure, including fundamental parameters, such as size and shape. After many years of development, the world’s first experiment on electron scattering off unstable nuclei is, recently, finally ready at the SCRIT (Self-Confining Radioactive isotope Ion Target) electron scattering facility [1] at the RIKEN RI Beam factory using a novel target forming technique, SCRIT. [2]

The SCRIT facility consist of a compact racetrack microtron, an electron storage ring equipped with the SCRIT system, an online isotope separator (ERIS), and a dc-to-pulse beam converter. RI beams produced at ERIS are converted to pulsed beams and injected to the SCRIT system. RIs trapped inside the SCRIT system play as stationary targets and electron beam stored in the ring are scattered from the RI targets. An electron spectrometer besides the SCRIT system analyzes the momentum and the trajectories of scattered electrons. The luminosity is measured continuously by a luminosity monitoring system placed at the downstream exit of the straight section of the electron storage ring. The usefulness of the SCRIT was demonstrated in the commissioning experiment. [3]

At ERIS, the RI production using the photofission of uranium is performed with the self-made UCx target. For instance, the rate of $^{132}$Sn and $^{137}$Cs are reached as 2.6$\times$10$^5$ ions/sec and 1.2$\times$10$^7$ ions/sec, respectively, with the 15-W electron beam irradiation on the UCx target including 28-g uranium. For $^{137}$Cs case, the luminosity is expected to reach about 2$\times$10$^{26}$ cm$^{-2}$s$^{-1}$, even at such a low production rate. In addition, there are plans to upgrade the electron beam power to 2 kW for electron elastic scattering from $^{132}$Sn.

In this contribution, we will introduce the SCRIT electron scattering facility and report the present status, the upgrade plan, and the progress of the experiment with unstable nuclei.

[1] M. Wakasugi et al., Nucl. Instr. Meth. B317 (2013) 668.
[2] M. Wakasugi et al., Nucl. Instr. Meth. A532 (2004) 216.
[3] K. Tsukada et al., Phys. Rev. Lett. 118 (2017) 262501

Speaker: Tetsuya Ohnishi (RIKEN Nishina Center)
• 2
Nucleosynthesis in Multinucleon Transfer Reactions

For decades, fragmentation, fission and fusion reactions are versatile tools to produce exotic nuclei in the lab. However, these standard nucleosynthesis reactions are reaching their limits. To enter new territory on the chart of nuclides, new pathways to exotic nuclei are needed. Mainly on the neutron-rich side, several thousand further isotopes are expected to exist, including most of the nuclei along the astrophysical r-process path.

Years ago, the idea arose to “revive” multi-nucleon transfer reactions to progress toward the neutron rich side of heavy and superheavy nuclei. Meanwhile, this option is investigated in nuclear physics labs worldwide. Beside new studies of transfer product kinematics and cross-sections, the development of suitable separation and detection techniques for heavy transfer products is ongoing. How promising are these new advances? So far achieved results allow us to get an impression on the potential which multi-nucleon transfer reactions provide for nucleosynthesis.

Speaker: Sophia Heinz
• 3
Multi-element beam delivery with the TRIUMF resonant ionization laser ion source

The resonant ionization laser ion source (RILIS) has developed into a reliable ion source that allows to ionize a majority of the elements. At TRIUMF's radioactive ion beam facility ISAC - which is short for Isotope Separator and Accelerator facility, a thick isol target is subjected to a primary proton beam from TRIUMF's 500MeV cyclotron for isotope production through fragmentation, fission and spallation. The isotope production target station can receive up to 100uA of protons onto target materials up to 238U. The radioactive isotopes produced need to be ionized in order to be extracted and delivered to experiments. The ion sources available at ISAC are a surface ion source, a gas discharge ion source and a resonant ionization laser ion source. One of the key characteristics of resonance ionization is its element selectivity, its versatility, and high efficiency. By now isotopes from 41 different elements have been ionized with the TRIUMF RILIS, and ionization schemes for another 22 elements have been developed off-line on stable isotopes. Current developments for RILIS aim for higher reliability, shorter setup and switch over time between elements, higher efficiency and improved suppression of non-laser ionized isobars. One way of achieving improved RIB delivery to experiments has been to set up laser ionization of two elements, so that experiments can switch between, laser on/off operation and laser ionization of two different elements. Another operation mode is concurrent laser ionization of two different elements - which is an operation mode that is particularly useful for 225Ac and 225Ra isotope collections.
I will present and discuss several examples of multiple element beam delivery at ISAC for experiments that were conducted in recent years and the instrumental and operational boundary conditions.

Speaker: Dr Jens Lassen (TRIUMF - Canada's particle accelerator centre)
• 4
Prospects for high resolution in-source spectroscopy using cross laser / atom beam geometry: Nuclear structure investigation on actinium isotopes with ISOLDE’s new ion source PI-LIST

Laser resonance ionization spectroscopy in the ion source coupled directly to the isotope production target has been proven to be a highly sensitive tool for nuclear structure investigations on isotopes with low production and extraction yields [1]. While the efficiency of this technique is unrivalled, the spectral resolution is ultimately limited by Doppler broadening. At the ion source temperature of ~2000 °C typically required for efficient operation, Doppler broadening results in a 1-10 GHz experimental resolution limit whereas precise measurements of nuclear magnetic and quadrupole moments often require resolving hyperfine structure splittings below the GHz regime.

A new laser ion source design has been implemented at ISOLDE recently to provide in-source spectroscopy capabilities down to experimental linewidths of 100 – 200 MHz, an order of magnitude below usual limitations. It is based on the high beam purity Laser Ion Source and Trap (LIST) [2, 3], featuring spatial separation of the hot cavity where potential ion beam contamination can arise from non-laser related ionization mechanisms such as surface ionization, and a clean laser-atom interaction region in an RFQ unit directly downstream where solely element-selective laser ionization takes place. In the so-called Perpendicularly Illuminated LIST (PI-LIST) [4], a crossed laser / atom beam geometry reduces the effective Doppler broadening by addressing only the transversal velocity components of the effusing atom ensemble.

Following the integration of this device as the standard tool for high resolution spectroscopy applications at the off-line mass separator facility at Mainz University [5, 6], we present its first on-line application at ISOLDE for nuclear structure investigations. Neutron-rich actinium isotopes in the region of assumed octupole deformation were probed, pinning down predictions of recent Energy Density Functional nuclear theories that incorporate reflection symmetry breaking [7].

Results of this experimental campaign, the applicability of the technique to ISOL facilities in general, its limits especially in terms of efficiency, and technical implementation challenges are discussed.

References
[1] V. Fedosseev et al., J. Phys. G: Nucl. Part. Phys. 44 084006 (2017)
[2] D. Fink et al., Nucl. Instr. Meth. B, 317 B, 417-421 (2013)
[3] D. Fink et al., Phys. Rev. X 5, 011018 (2015)
[4] R. Heinke et al., Hyperfine Interact 238, 6 (2017)
[5] D. Studer et al., Eur. Phys. J. A 56, 69 (2020)
[6] T. Kron et al., Phys. Rev. C 102, 034307 (2020)
[7] E. Verstraelen et al., Phys. Rev. C 100, 044321 (2019)

Speaker: Reinhard Heinke (CERN)
• Coffee Break S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Session 2 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 5
Precision laser spectroscopy of fast radioactive beams and trapped ions
Speaker: Prof. Ruben de Groote
• 6
Development of Ti:sa laser ion sources for S3-LEB at SPIRAL2-GANIL

At GANIL-SPIRAL2 and LPC Caen the Super Separator Spectrometer-Low Energy Branch (S$^3$-LEB) [1] project is under development to study exotic nuclei by In-Gas Laser Ionization Spectroscopy (IGLIS) to extract ground-state properties, such as nuclear mean-square charge radii $δ$, magnetic dipole $μ$ and electrical quadrupole $Q$ moments, and nuclear spins $I$. The nuclides of interest will enter a gas cell where thermalization and neutralization will take place under a constant gas flow. A supersonic gas jet will be created by a de Laval nozzle with a high Mach number $M$ [2], resulting in a collimated low-temperature and low-density environment, where IGLIS will be subsequently performed. The in-gas-jet laser spectroscopy method will result in higher spectral resolution without loss in the efficiency in comparison to the in-gas-cell spectroscopy studies [3].

A crucial aspect of the S$^3$-LEB setup is the laser system, which has been extensively developed at GISELE offline laser laboratory for the purpose of performing mid- to high-resolution spectroscopy [4]. Having multiple laser systems with different resolving powers is necessary for performing measurements either in-gas-cell or in-gas-jet environments. In order to resolve hyperfine structures and extract nuclear properties of interest, one requires wide scanning range, narrow spectral linewidths, adequate temporal and spatial laser overlap and reliable recording of the measurement parameters. The progressive development of the titanium:sapphire laser systems in our laboratory has led to successful measurements of a few elements of interest for the day-1 experimental program like erbium, tin and palladium. This development work and latest laser-spectroscopy results will be presented.

[1] F. Déchery et al, Nucl. Instrum. Meth. B 376, 125 (2016). doi: 10.1016/j.nimb.2016.02.036
[2] R. Ferrer et al. Phys. Rev. Res. 3, 043041 (2021). doi:10.1103/PhysRevResearch.3.043041.
[3] R. Ferrer et al. Nat. Commun. 8, 14520 (2017). doi: 10.1038/ncomms14520
[4] J.Romans et al., Atoms 10(1), 21 (2022), doi: 10.3390/atoms10010021

Speaker: Jekabs Romans (KU Leuven)
• 7
Advances at the CRIS experiment for the laser spectroscopy of short-lived radioactive atoms and molecules

The collinear resonance ionization spectroscopy (CRIS) experiment at the ISOLDE facility at CERN specializes in performing high-sensitivity laser spectroscopy on species with production rates as low as 101-102 nuclei per second. Recently, thanks to the ability of the technique to perform both high-resolution spectroscopy at high precision and low-resolution spectroscopy with a short experimental runtime, the CRIS experiment has expanded its activities to include laser-spectroscopic campaigns on radioactive molecules.

Following the first laser spectroscopy of radium monofluoride (RaF) [1], further CRIS campaigns on beams of short-lived radioactive molecules are being envisioned. Actinium monofluoride (AcF) has been identified as a promising candidate system for the first measurement of a nuclear Schiff moment across the nuclear chart [2], and a CRIS experiment to pin down the electronic structure of AcF for the first time has been planned for the Fall of 2022.

Additionally, to further improve the performance of the CRIS experiment, a voltage-scanning setup has been recently installed, to combine the techniques of frequency and voltage scanning. Commissioning tests with stable beams of Al and Ag have demonstrated that combining the two scanning approaches can accelerate the experimental runtime by a factor of 4 while ensuring that alterations in the ion trajectories are minimized. Additionally, a new laser-ablation ion source based on a radiofrequency ion guide within a gas cell is under construction, aiming to improve the ability of the CRIS experiment to optimize the selection of a laser scheme for atomic and molecular studies.

This contribution will present the recently implemented and planned upgrades at CRIS along with recent results.

References
[1] R. F. Garcia Ruiz et al., Nature 581 (2020) 396-400.
[2] L. V. Skripnikov et al., Physical Chemistry Chemical Physics 22 (2020) 18374-18380.

Speaker: Mr Michail Athanasakis-Kaklamanakis (CERN, CH-1211 Geneva 23, Switzerland; KU Leuven, B-3001 Leuven, Belgium)
• 8
Atomic structure investigation of curium by laser mass spectroscopy

As a transuranium element with proton number $Z=96$, curium is considered as one of the “minor actinides” in spent nuclear fuel. It is produced during burn-up by a series of nuclear reactions from $^{238}$U; spent nuclear fuel contains about $20$ g/tonne. Nineteen curium isotopes from $^{233}$Cm to $^{251}$Cm are known [1], with some exhibiting long half-lives between a few days and $10^{7}$ years. As these include strong $\alpha$-emitters as well as fissionable isotopes with large fission cross section, it is considered for transmutation as a highly radiotoxic contaminant. Targeted production of curium isotopes is achieved by neutron-irradiation of plutonium isotopes in high flux research reactors. As a mid-range actinide element within the Periodic Table, Cm has an electronic odd-parity ground state configuration $5f^{7}6d7s^{2}\,^{9}D^{o}_{2,3,4,5,6}$ and a second nearby located even-parity configuration $5f^{8}7s^{2}\,^{7}F_{0,1,2,3,4,5,6}$. Accordingly, its atomic structure is very rich, highly complex and so far only known to some degree.
Resonance ionization mass spectroscopy (RIMS) at the RISIKO mass separator of Mainz University has been applied for off-line studies of the Cm atomic structure within a series of investigations on long-lived actinides [2,3]. Due to its high ionization efficiency and outstanding elemental selectivity the technique is an excellent tool for high precision optical spectroscopy of atoms, especially regarding minuscule and rare samples, for the selective production of ions of a given element and, finally, for selective and sensitive ultra-trace determination [4]. A sequence of carefully selected optical transitions is used as resonant laser excitation ladder up to ionization. The combination with high transmission mass separation permits for quantitative low background detection of individual ions within an isotopically pure ion beam [5]. The laser system and the layout of the laser ion source unit are the central aspects of RIMS and determine the quality and significance of the spectroscopic data [5,6,7]. In Cm, three first excitation steps from the $5f^{7}6d7s^{2}\,^{9}D^{o}_{2}$ atomic ground state to the $5f^{7}6d7s7p\,^{9}D_{3}$, $5f^{8}6d7s\,^{9}D_{3}$, and $5f^{7}6d7s7p\,^{7}D_{2}$ levels were studied for $^{248}$Cm. Based on all these steps, Rydberg levels were identified and their convergences were analyzed to deliver a precise value of the first ionization potential (IP). The Rydberg analysis was complicated due to the high spectral line density and strong configuration interactions. The IP value was independently confirmed by involving the field ionization approach with varying external electric field and applying the saddle point model. An IP value of $48330.73(18)\,\text{cm}^{-1}$ was obtained from the weigthed mean of the results from both methods; which certifies a slight underestimation of the former literature IP value of $48324(2)\,\text{cm}^{−1}$ by Köhler et al., measured in $1996$ [8].
References
1. Habibi, A. et al., Radioanal. Nucl. Chem. 329 (2021).
2. Zhang, K. et al., Phys. Rev. Lett. 125 (2020).
3. Nothhelfer, S. et al., Phys. Rev. C 105 (2022).
4. Bosco, H. et al., Sci. Adv. 7 (2022).
5. Kieck, T. et al., Nucl. Instrum. Methods Phys. Res. A 945 (2019).
4. Bosco, H. et al., Sci. Adv. 7 (2022).
5. Mattolar, C., Ph.D. thesis, Johannes Gutenberg University Mainz (2010).
6. Sonnenschein, V. et al., Laser Phys. 27 (2017).
7. Sonnenschein, V. et al., Hyperfine Interact. 241 (2020).
8. Köhler S. et al., Spectrochim. Acta B 52 (1997).

Speaker: Nina Kneip (Johannes Gutenberg University Mainz)
• 12:30 PM
Lunch
• Session 3 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 9
Targets for In-Flight Separators with Intense Beams

Production of rare ions from projectiles in flight is a universal technique for most nuclides. Besides fragmentation and fission in-flight also fusion and multi-nucleon transfer can be used for production. A separator is needed before inflight identification of ions and experiments can follow.
With more intense beams the first challenge is the target itself, because heavy ion beams lead to a high density of energy deposition. Cooling mechanisms need to be integrated and radiation damage be considered. Mechanical stress is another limit which especially becomes sever as dynamic stress in case of pulsed beams.
The basic parameters for optimisation of yields will be discussed, with respect to production cross sections, target thickness, energy-loss in the target as a limiting factor. The latest high intensity facilities BigRIPS/RIKEN, ARIS/FRIB, Super-FRS/FAIR, S3/GANIL, HFRS/HIAF, IF/RAON are good examples.
It is the direct integration into an isotope separator which causes most difficulties. The systems have to work in vacuum as with the intense beam vacuum windows are usually ruled out. The separator must be designed in such a way that intense beam must not hit a normal vacuum chamber but only dedicated beam catchers. As the expensive separator should be versatile for many nuclides, the remaining primary beam can hit many positions and due to a different magnetic rigidity will also be focused differently than the wanted fragment beam. All this has to be considered in the design of the separator. Contrary to dedicated beam dumps for production of only one particle species at one fixed energy the design becomes much more complicated. It will be shown in the case of Super-FRS.
It also means handling of the components hit by intense beams have limited lifetimes and require a bigger infrastructure for handling of radioactive parts around it, as will be shown in the case of Super-FRS.

Speaker: Helmut Weick (GSI Helmholtzzentrum für Schwerionenforschung)
• 10
Operational experiences of high-power production target and high-power beam dump at BigRIPS separator at RIKEN RI beam factory

A water-cooled rotating target and a water cooled stational beam dump to withstand beam powers of 82 kW corresponding to the $^{238}$U beams with the energy of 345 MeV/nucleon and the intensity of 1 particle $\mu$A, were developed as the target and beam dump system for the BigRIPS separator at RIKEN RI Beam factory in 2007. They have been successfully operated without sever trouble with the beam powers of up to 15 kW. Operational experiences of these systems over the 15 years will be presented at the conference. Results of measurements of the beam-spot temperatures for the target and the beam dump with various beams from RIBF accelerators were compared with the thermal model calculations and validity of the design will be discussed. Radiation damage to the system equipment, although not yet relevantly observed, will also be discussed along with PHITS$^{1)}$ simulation results.

1) T. Sato et al., J.Nucl.Sci.Technol.55, 684-690 (2018).

Speaker: Dr Koichi Yoshida (Dr.)
• 11
Improved isotope intensity and purity from a new spallation-driven proton-to-neutron converter at ISAC-TRIUMF

A spallation-driven, proton-to-neutron converter target has been developed and irradiated at the ISAC-TRIUMF facility, focusing on the production of radioactive ion beams (RIBs) of neutron-rich fission fragments and limiting by design the production of their neutron-deficient isobaric contaminants. So far, fission fragment RIBs have been produced at ISAC-TRIUMF with the ISOL method by impinging the incoming proton beam onto a 10-cm stack of hundreds of closely packed actinide composite foils in a cylindrical tantalum oven. One important issue that users experience is the presence of neutron-deficient isobaric contamination that frequently dominates the beam of interest and prevents the successful outcome of the experiment. A new proton-to-neutron converter target assembly has been designed with the intent of reducing the in-target production of neutron-deficient isobaric contaminants by generating an intense spallation neutron field from a tungsten converter, positioned just downstream of an annular uranium carbide target. The fast neutrons subsequently induce fission reactions in the actinide material, producing predominantly neutron-rich radioisotopes while limiting the production of the neutron-deficient, spallation-induced reaction products. In addition to the different distribution of produced isotopes, a thermal decoupling between the target and converter components, as well as the reduction of long-lived and highly radiotoxic alpha emitting isotopes offer additional benefits that allow high-power irradiations and more efficient isotope release.
This contribution presents the combined numerical and experimental optimization process that led to the final target design and focuses on the successful online results obtained at the ISAC-TRIUMF facility from several independent irradiation campaigns. The extensive online beam time dedicated to this target has allowed for precise characterization of its performance by exploring a wide parameter space and has already allowed the delivery of more exotic neutron-rich isotope beams of Rb, Cs, Zn and Ga, enabling successful completion of previously unfeasible experiments. Further investigations of Sn isotopes are planned for the summer of 2022.

Speaker: Luca Egoriti (TRIUMF)
• Coffee Break S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Poster Session S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Session 4 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 12
Br-defined isochronous mass spectrometry: a new tool for precision mass measurements of short-lived nuclei

Nuclear mass spectrometry is an intensively developing field in modern experimental physics. Among all the state-of-the-art methods, isochronous mass spectrometry (IMS) at storage rings plays an important role in broadband mass measurements of short-lived nuclei. However, high mass resolving power can be achieved only in a limited m/q-range with good isochronicity with the conventional IMS. To improve the situation, we have developed a brand new technique, the Bρ-defined IMS, at the cooler storage ring CSRe in Lanzhou, and used it in mass measurements of neutron-deficient, fp-shell nuclides produced by the fragmentation of a 58Ni beam. Using the simultaneously determined revolution times and velocities of the stored ions, the relation between ions’ magnetic rigidities and orbit lengths is established, allowing to determine the magnetic rigidity of any stored ion according to its orbit length. Consequently, m/q values of the unknown-mass nuclides are determined. High mass resolving power has been achieved covering a large m/q-range over the full B-acceptance of the storage ring, starting a new era of the IMS. The masses of a series of nuclides are determined with high precision in one single setting. Among them, masses of 46Cr, 50Fe, 54Ni are determined with relative uncertainties of (5~6)*10-8, providing important input data for weak interaction physics.

Speaker: Prof. Meng Wang
• 13
Applying Heavy-Ion Storage Rings for Precision Experiments at the Intersection of Atomic, Nuclear and Astro-Physics

The storage of freshly produced radioactive particles in a storage ring is a straightforward way to achieve the most efficient use of such rare species as it allows for using the same rare ion multiple times. Employing storage rings for precision physics experiments with highly-charged ions (HCI) at the intersection of atomic, nuclear, plasma and astrophysics is a rapidly developing field of research.
There ae presently three accelerator laboratories, GSI Helmholtz Center Germany (GSI), Institute of Modern Physics in China (IMP), and Nishina Research Center in Japan (RIKEN) operating heavy-ion storage rings coupled to radioactive-ion production facilities. The experimental storage ring ESR at GSI, the experimental cooler-storage ring CSRe at IMP, and the Rare RI ring R3 at RIKEN offer beams at energies of several hundred A MeV. The ESR is capable to slow down ion beams to as low as 4 A MeV (beta=0.1). Beam manipulations like deceleration, bunching, accumulation, and especially the efficient beam cooling as well as the sophisticated experimental equipment make rings versatile instruments. The number of physics cases is enormous. The focus here will be on the most recent highlight results achieved within FAIR-Phase 0 research program at the ESR.
First, the measurement of the bound-state beta decay of fully-ionized 205Tl was proposed about 35 years ago and was finally accomplished in 2020. Here, the ESR is presently the only instrument enabling precision studies of decays of HCIs. Such decays reflect atom-nucleus interactions and are relevant for atomic physics and nuclear structure as well as for nucleosynthesis in stellar objects.
Second, the efficient deceleration of beams to low energies enabled studies of proton-induced reactions in the vicinity of the Gamow window of the p-process nucleosynthesis. Proton capture reaction on short-lived 118Te was attempted in 2020 in the ESR. Here, the well-known atomic charge exchange cross-sections are used to constrain poorly known nuclear reaction rates.
The performed experiments will be put in the context of the present research programs at GSI/FAIR and in a broader, worldwide context, where, thanks to fascinating results obtained at the presently operating storage rings, a number of new exciting projects is planned. Experimental opportunities are being now dramatically enhanced through construction of dedicated low-energy storage rings, which enable stored and cooled secondary HCIs in previously inaccessible low-energy range. The first such facility, CRYRING, has just been utilized for precision experiments at GSI with decelerated beams of HCIs transferred from the ESR.
Thanks to the fascinating results obtained at the ESR, the CSRe and the R3 as well as to versatile experimental opportunities, there is now an increased attention to the research with ion-storage rings worldwide. Dedicated ring facilities are proposed for ISOLDE at CERN, TRIUMF, LANL, and JINR.

Speaker: Yury Litvinov (GSI Helmholtz Center)
• Tuesday, October 4
• Session 5 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 14
Studies of the two-step scheme with a $^{132}$Sn beam for next-generation RI-beam production method in the medium-heavy very-neutron-rich region

The usefulness of the two-step scheme with a $^{132}$Sn beam was investigated [1], which was proposed for efficient production of medium-heavy very-neutron-rich radioactive isotopes (RI) [2] as an alternative method to the direct production by means of in-flight fission of a $^{238}$U beam (one-step scheme). The system of the two-step scheme consists of an isotope-separation online (ISOL) system and an in-flight fragment separator. Long-lived neutron-rich RIs (e.g., $^{132}$Sn) are produced by ISOL with a thick U target and a high-intensity proton beam in the first step, and more neutron-rich RI beams (e.g., $^{128}$Pd) are produced by a projectile fragmentation from the re-accelerated less-exotic RI beams in the second step.
We measured production cross sections of very neutron-rich RIs around a N = 82 region beyond $^{125}$Pd, up to which the cross sections had already been measured at GSI [3], with a 278-MeV/nucleon $^{132}$Sn beam produced by the BigRIPS separator [4] impinging on a 5.97-mm Be target. The yields obtained by the two-step and one-step schemes were estimated based on the measured cross sections, and we examined whether and to what extent the two-step scheme at future 1-MW beam facilities can reach further into the neutron-rich regions. This comparison suggests that the two-step scheme with the $^{132}$Sn beam provides yields $\gt$40-times higher than those with the one-step scheme for the very neutron-rich N = 82 region. Moreover, by using various RI beams over the nuclear chart from ISOL, certain regions of very neutron-rich RIs around N = 50, 60, 82, and 90 regions, including the supernova $r$-process path, can be produced with greater yields than by the one-step approach.
References
[1] H. Suzuki et al., Phys. Rev. C 102, 064615 (2020).
[2] K. Helariutta et al., Eur. Phys. J. A 17, 181 (2003).
[3] D. Pérez-Loureiro et al., Phys. Lett. B 703, 552 (2011).
[4] T. Kubo, Nucl. Instr. and Meth. B 204, 97 (2003).

Speaker: Hiroshi Suzuki (RIKEN Nishina Center)
• 15
LISE$_{cute}^{++}$, the latest generation of the LISE$^{++}$ package, to simulate rare isotope production with fragment-separators

The LISE$^{++}$ software for fragment separator simulations has undergone a major update. The package, widely used at rare isotope beam facilities, can be used to predict intensities and purities of rare isotope beams and for planning and running of experiments using in-flight separators. It is especially useful for radioactive beam production as its results can be quickly compared to on-line data. The LISE$^{++}$ package has been ported to the Qt-framework in order to support modern compilers and computing methods. The benefits include 64-bit operation and LISE$^{++}$ availability on three different platforms: Windows, macOS and Linux. In addition, the porting provides the ability to take advantage of future computational improvements. The updated package is named LISE$_{cute}^{++}$ to indicate a major step forward from the previous Borland-based versions. The LISE$_{cute}^{++}$ package remains essentially identical for all platforms, keeping all previous versions functionality with implementation of new features and utilities. In addition to porting to the new platform, new features and modifications been added, such as 3-D Monte Carlo plotting including 3-D envelopes. The codes ETACHA4 and GEMINI++ were ported to a GUI and implemented in the package. In context of production models, new utilities have been developed such as a minimization procedure using the Abrasion-Ablation model to adjust its parameters based on experimental projectile-fragmentation cross-sections and an initial fissile nuclei analyzer.
The next steps in the LISE$_{cute}^{++}$ package development will be discussed in this presentation. These include the creation of a LISE$_{core}^{++}$ library that will allow integration of LISE$^{++}$ calculations within control systems. This will directly assist in the tuning of fragment separators. Code parallelization will allow use of modern computing architecture and are essential to achieve faster computation.

Speaker: Oleg Tarasov (FRIB / MSU)
• 16
New developments for experiments at the three branches of the Fragment Separator FRS

The FRagment Separator FRS at GSI features three branches for experiments with in-flight separated beams, the symmetric branch, the storage-ring branch connected to the Experimental Storage Ring and CRYRING complex (ESR/CRYRING), and the target hall branch to various caves, where experimental setups for Reaction experiments with Relativistic Radioactive Beams (R3B) and for Biomedical Applications of Radioactive ion Beams (BARB) are located. The symmetric branch is used mainly for spectrometer experiments and implantation experiments, where the nuclei of interest are completely slowed down and thermalized and then studied by decay- or mass-spectrometry. In order to study the most exotic nuclei, the rate of the nuclei of interest is often a critical parameter. For a significant rate increase, a high-transmission ion-optical mode and very thick production targets making use of two-step reactions have been developed and tested; results obtained with Pb and Xe fragment beams will be reported.
At the ESR, an energy-isochronous ion-optical mode has been available for direct mass measurements of very short-lived nuclei for more than two decades. With revolution-time measurements only, the high mass-over-charge accuracy and resolving power is limited to a narrow window in the magnetic rigidity. This statement has been proven first by using slits at the second focal plane of the FRS. Instead of an independent magnetic rigidity measurement, one can also measure the velocity with two TOF detectors as it is foreseen for the CR at FAIR and meanwhile implemented at the CSRe in Lanzhou. An equivalent way is to simultaneously measure the magnetic rigidity and the revolution frequency of each circulating stored ion. Calculations show that an upgraded position sensitive TOF detector, located at a dispersive position in the ESR lattice, will improve the accuracy and the mass resolution without limiting the intensity of the stored exotic nuclei.
The third branch of the FRS leads to the target hall with the medical cave as one possible destination. Recently a joint effort between the FRS and the biophysics groups of GSI was started to perform biomedical experiments relevant for hadron therapy with positron emitting carbon and oxygen beams. The ion-optics and diagnostics for this new branch have been prepared and pure positron emitting $^{15}$O-ions were provided to the medical cave for the first time. An overall conversion efficiency of about $6\times 10^{-4}$ for $^{15}$O fragments per primary $^{16}$O projectile was reached.

Work partly supported by ERC AdG no. 883425 (BARB)

Speaker: Emma Haettner (GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany)
• 17
Current Status of In-flight Fragment Separator for RAON

Speaker: Do Gyun Kim (Institute for Basic Science)
• Coffee Break S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Session 6 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 18
VAMOS : Performances and Physics Opportunities

The Variable Mode Spectrometer (VAMOS) is a large acceptance magnetic spectrometer o at the Grand Accélérateur National d'Ions Lourds (GANIL), France, that allows to reconstruct charged-particle trajectories. The performances of the spectrometer allow to identify a large range of products in terms of mass, nuclear charge, ionic charge state and velocity vector from nuclear reactions. During the last years, different experimental campaigns were carried out using the VAMOS spectrometer both, in a single mode, such as the fission program in inverse kinematics, or coupled with additional detectors. Particularly remarkable was the coupled operation with the Advanced GAmma Tracking Array (AGATA) exploring physical cases covering nuclear structure and nuclear reactions studies. The highly-segmented silicon array (MUGAST) campaign offered the opportunity to study nuclear structure and astrophysics from direct reactions benefiting from exotic SPIRAL1 beams.
Along with the different campaigns, the VAMOS spectrometer underwent continuous improvement in terms of detection and electronics that allowed to exploit its capacity reaching unprecedented results.
In this talk, I will presented an overview of the recent experimental campaigns that were carried out with the VAMOS spectrometer as well as the improvements of the setup that drove the spectrometer and the associated detectors to the current state.

Speaker: Diego Ramos (GANIL/CEA-CNRS)
• 19
Commissioning results of ISOL beam lines with $^{133}$Cs and $^{120}$Sn beams at Rare Isotope Science Project

Radioactive isotope (RI) beam techniques are expanding the playing field of nuclear physics, and new insight of nuclei are given by continuously experimental and theoretical efforts. Reaccelerated RI beams based on ISOL technique is informative for more precise measurements with high statistics, because these beams have both of excellent quality and high intensity. In addition, such RI beams are utilized to RI productions, the playing field can be expanded to more exotic region. Very low-energy RI beams extracted from ISOL are also convenient for not only nuclear physics but also material science and cancer therapy. For these purposes, we are developing a high power ISOL facility.

ISOL system at Rare Isotope Science Project (RISP) consists of a proton cyclotron, a target ion source (TIS), a pre-mass separator, a radio frequency quadrupole cooler buncher (RFQCB), an electron beam ion source (EBIS) charge breeder, and an A/q separator. Experimental Physics and Industrial Control System (EPICS) was adopted for the ISOL control system as a standard framework. Construction of the system and optical components alignment were completed on 2020, and now is commissioning with stable ion beams. Since we developed a surface ionization ion source and a Laser ion source, the commissioning combining all devices is performed by using $^{133}$Cs, and $^{120}$Sn beams from the TIS. As a result, we found the pre-mass separator beam line setting condition with required mass resolving power (> 400) and 100% beam transmission efficiency. Although the beam commissioning of the A/q separator is undergoing, the beam was able to transport from the TIS to the end of ISOL beam line, that is the entrance of RFQ accelerator system.

In this presentation, the beam commissioning results for the pre-mass separator and the A/q separator will be reported. In addition, future test plans and schedule will be discussed.

Speaker: Takashi Haashimoto (Institute for Basic Science, Rare Isotope Science Project)
• 20
SECAR: A recoil separator for nuclear astrophysics

The recoil mass separator, SECAR (SEparator for CApture Reactions), recently commissioned at the Facility for Rare Isotope Beams (FRIB), enables direct measurements of proton- and alpha-capture reaction rates on proton-rich nuclei. SECAR will take advantage of radioactive beams produced by FRIB via projectile fragmentation, which are then stopped, and reaccelerated to astrophysical energies at the ReA3 facility. After a reaction occurs by impinging the reaccelerated beam on a hydrogen or helium SECAR target in gaseous or solid form, the reaction recoils are counted at SECAR, where a sequence of magnets and Wien filters separate them from the unreacted beam. The preparation of the SECAR system for accommodating its first science measurements, including the development of alternative ion beam optics and a novel SECAR tuning technique using Machine Learning, along with preliminary results will be presented.

Speaker: Fernando Montes (Facility for Rare Isotopes Beams (FRIB))
• 21
New developments for reaction study at low energy with radioactive beams at RIKEN RI beam factory

Reaction studies with radioactive (RI) beams are one of most important topics in nuclear physics. Efforts have been made to the high-energy reaction, such as spallation/fragmentation. In recent years, low-energy reaction for heavy ion such as transfer and fusion are required. In addition, reaction at a few ten MeV/u are desired to investigate the energy dependence of cross sections for the purpose of technological developments for nuclear transmutation of long-lived fission products.

At the RIKEN RI beam factory, the ZeroDegree spectrometer (ZDS) is one of basic and critical devices for the identification of reaction residues and it is well applied for heavy-ion reactions at energy above 100 MeV/u. Indeed, proton- and deuteron-induced spallation reactions have been successfully studied at 200 MeV/u. Towards an energy with a few ten MeV/u, reaction studies encounter difficulties in large energy losses and serious charge-state distributions, which cause a challenge in making reaction target as well as in the identification of reaction products.

Aiming at performing reaction study at 50 MeV/u, new developments have been made to overcome the difficulties mentioned above. New reaction targets made by gaseous hydrogen and deuterium with a high pressure and a low temperature to minimize the energy loss. The dispersive mode of the ZeroDegree spectrometer to obtain a high momentum resolution as well as to minimum the detector material in mid-focal planes which makes additional charge-state distribution. In addition, a new ionization chamber (IC) with 15 layers and a depth of 1000mm has been developed and is installed at the end of ZDS for the measurement of both energy loss ΔE and total energy E by stopping all the particles, leading to a new identification method for reaction residues using ΔE, E, TOF and Bρ.

With these new developments, cross sections on proton and deuteron of long-lived fission product 107Pd have been successfully obtained at 50 MeV/u, showing a clear energy dependence by comparing to the data obtained at high energies. In the presentation, the detailed information on the developments and performances of these new devices in this experiment will be discussed.

Speaker: He Wang (RIKEN)
• 12:20 PM
Lunch (IAC meeting) S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Session 7 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 22
The WASA-FRS project at GSI and its perspective
Speaker: Prof. Takehiko Saito
• 23
Ultraviolet Spectroscopy of the Actinium-229 beta decay: the first observation of the radiative decay of the 229Th low-energy isomer

A unique feature of thorium-229 is its isomeric first excited state with an exceptionally low excitation energy, proposed as a candidate for future nuclear optical clocks [1]. The small nuclear moments are expected to outperform the accuracy of current state-of-the-art atomic clocks by about an order of magnitude [2]. The current best values of the excitation energy are 8.28(17) eV and 8.10(17) eV[3,4]. These were determined using two different measurement techniques whereby the isomer is populated in the alpha decay of uranium-233. The development of an optical clock requires, however, knowledge of the excitation energy by at least an order of magnitude more precise. Spectroscopic experiments searching for a direct signature of the radiative decay have to-date been unsuccessful, partially due to the background induced in the preceding alpha decay.

An alternative approach using the beta decay of actinium-229 is studied as a novel method to populate the isomer with high efficiency and in low background conditions [5]. Produced online at the ISOLDE facility, actinium is laser-ionized and implanted into a large-bandgap crystal in specific lattice positions, suppressing the electron conversion decay channel of the isomer. A favourable feeding pattern is significantly increasing the population of the isomer compared to uranium-233 and the lower energy deposit of the beta compared to the alpha decay results in a significantly reduced luminescence background.

In this contribution, a dedicated setup for the implantation of a francium/radium/actinium-229 beam into large-bandgap crystals and the vacuum-ultraviolet spectroscopic study of the emitted photons will be presented. From the results obtained during a first measuring campaign using MgF${}_2$ and CaF${}_2$ crystals as host material it can be concluded that the radiative decay of the thorium-229 isomer has been observed for the first time, the excitation energy of the isomer has been determined with a factor of 5 improved uncertainty and the ionic lifetime in a crystalline environment was determined.

[1] E. Peik et al., Europhys. Lett. 61, 2 (2003)
[2] C. Campbell et al., PRL 108, 120802 (2012)
[3] B. Seiferle et al., Nature 573, 243-246 (2019)
[4] T. Sikorsky et al., PRL 125, 142503 (2020)
[5] M. Verlinde et al., Physical Review C, 100, 024315 (2019)

Speaker: Sandro Kraemer (KU Leuven)
• 24
Development of new ionization chamber specialized in high-Z beam

RI Beam Factory (RIBF) at RIKEN Nishina Center for Accelerator-Based Science provides various RI beams from 238U 345 MeV/u primary beam. Here we report the new experimental results on high-Z beam production. The ionization chamber (IC) for energy-loss measurement is an essential detector for deducing the atomic number (Z) in flight in the BigRIPS spectrometer to identify the particles. The conventional IC with a low-cost gas mixture of 90% argon and 10% methane does not provide sufficient Z resolution for high-Z beams, especially Z>80 region, around 200-250 MeV/u which is a typical energy at RIBF.

Because the high-Z beam is more likely to capture electrons in material than the low-Z beam, which mostly keeps fully stripped, the number of charge-state changes in the IC gas affects the energy-loss distribution. For example, He-like state of U beam at 200 MeV/u, which is the most abundant charge state in material, changes the charge state approximately four times in the IC with the argon-based gas mixture, which is not sufficient for the energy-loss measurements. To enhance the Z resolution of the high-Z particles, xenon gas with an larger cross section of the charge-state changing is promising. Approximately 70 times of the charge-state changes of U beam at 200 MeV/u in the IC with a gas mixture of 70% xenon and 30% methane are expected to narrow the width of the energy-loss distribution.

The Z resolution of the IC with the argon-based and xenon-based gas mixtures was measured at BigRIPS using cocktail beam in the Z=60-90 region with 200-240 MeV/u. The results show the xenon-based gas mixture dramatically improves the Z resolution for Z>70 particles compared with the argon-based gas mixture. Furthermore, the xenon gas was found to be effective for the Z identification in this energy region, since the same energy-loss is obtained for even different incident charge states. In conclusion, the xenon-based gas IC strongly promotes the beam delivery of the high-Z region with the clear particle identification from BigRIPS spectrometer.

Speaker: Masahiro Yoshimoto (RIKEN Nishina Center)
• Coffee Break S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Session 8 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 25
Commissioning of the Advanced Rare Isotope Separator ARIS at FRIB

Commissioning of the in-flight separator system ARIS began in early 2022 at the Facility for Rare Isotope Beams (FRIB) at Michigan State University. The system consists of up to three stages of achromatic separation and can deliver beams to various experimental stations for nuclear and astrophysics studies, as well as other societal needs. In-flight products are generated with beams from a driver linac designed to deliver up to 400 kW of 200 MeV/u uranium ions on-target, and higher energies for lighter ions. The separator is nominally designed to transmit beams of phase space distribution widths up to 40 mrad and +/-5% for momentum. To enhance the transmission efficiency over various legacy beam lines, momentum compression can be imposed at the first degrader stage. Modes with no compression are also developed to avoid using a degrader in the preseparator. The first cycle of experiments began in March at about 1 kW of primary beam. Operation at higher power and beam energies has been progressing. A description of the system will be given along with results from commissioning and operational experience.
Funding Agency:
Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.

Speaker: Mauricio Portillo (FRIB MSU/USA)
• 26
Recent Progress of ISOL Facility at RISP

The RAON heavy ion accelerator facility is currently in the stage of commissioning under the Rare Isotope Science Project (RISP) launched in 2011. The RAON is planned to utilize an advanced rare isotope beam produced with a high power target by the Isotope Separation On-Line (ISOL) facility, aiming to deliver high purity and intense, neutron-rich rare isotope beams to the post-accelerator and experimental facilities. The RAON ISOL facility consists of a target/ion source module surrounded by movable shielding blocks in a bunker, remote handling facilities for the target operation, a pre-mass separator, a RFQ cooler buncher, an EBIS charge breeder, and an A/q separator. Installation and alignment of the ISOL facility were completed in June 2021. The target/ion source module allows us to bombard a thick target with a 70 MeV proton beam of RAON, producing a variety of rare isotope beams. The produced isotope beams extracted from the target/ion source can be transported to a pre-mass separator at energies up to 60 keV, and will be cooled in a RFQCB. Cooled ion beams can be sent to two different experimental facilities, such as a Mass Measurement System and a Collinear Laser Spectroscopy in ISOL experimental hall. Alternatively, for post–acceleration of ion beams, the singly charged ion beam of interest can be bunched to 10$^{8}$ ions and then delivered to the EBIS charge breeder through the EBIS branch system. The preparation of multi charged ion beams for the post-acceleration using the superconducting linac of SCL3 will be carried out through the EBIS charge breeder and A/q separator to match the energy of 10 keV/u with A/q<6 with the requirement of RAON Injector.
The first commissioning experiment of the ISOL system started from March 2021 using the $^{133}$Cs and $^{120}$Sn stable beams produced from the target container combined with the surface ion source and laser Ion source. The stable beam experiments have demonstrated the overall functioning of the RAON ISOL system, and we are planning to carry out the first RI beam test using the SiC target with 70 MeV proton of cyclotron at the end of 2022.

Speaker: Jinho Lee (RISP)
• 27
Development and Operation of High-Power Target Systems at TRIUMF

With over five decades of experience in the production of accelerator-based secondary particles for science, TRIUMF ensures that Canada remains on the leading edge of supplying radioisotopes, neutrons, photons, and muons enabling fundamental science in the fields of nuclear, particle and astrophysics, as well as solid state and medical sciences and applications.

ISAC-TRIUMF is the only ISOL facility worldwide that routinely produces radioisotope beams from targets irradiated in the high-power regime in excess of 10 kW. TRIUMF’s current flagship project ARIEL, Advanced Rare IsotopE Laboratory, will add two new target stations providing isotopes to the existing experimental stations in ISAC I and ISAC II at keV and MeV energies, respectively. In addition to the operating 500 MeV, 50 kW proton driver from TRIUMF’s main cyclotron, ARIEL will make use of a 30 MeV, 100 kW electron beam from a newly in-house designed and build superconducting linear accelerator. Together with additional 200 m of radioisotope beamlines within the radioisotope distribution complex, this will put TRIUMF in the unprecedented capability of delivering three isotope beams to different experiments, while producing radioisotopes for medical applications simultaneously – enhancing the scientific output of the laboratory significantly.

The results of 20 years of operational experience and target and ion source developments at ISAC is being used to design and build the ARIEL target stations. These new designs are, in turn, applied to inform a fundamental ISAC target systems refurbishment campaign that addresses ageing infrastructure, as well as the raising demand for new beams, increased beam intensity and purity, facility uptime, radiation safety and operational efficiency.

Speaker: Alexander Gottberg (TRIUMF)
• 28
The Super Separator Spectrometer (S3) at GANIL-SPIRAL2
Speaker: Prof. Herve Savajols
• Poster Session S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Wednesday, October 5
• Session 9 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 29
Target- and ion source development at CERN-ISOLDE

At the CERN-ISOLDE radioactive ion beam facility, the thick targets are irradiated using a beam of 1.4 GeV-protons. One of ISOLDE's features is the large choice of ion source types and targets materials available on the menue, enabling us to select the optimial combination for optimal intensity and purity of the isotopes requested by the ISOLDE Users. Ever increasing demands in terms of isotope production yield, beam purity, and overall reliability of the employed systems are drivers of the continous development efforts.
Over the last years, CERN has invested especially in facilities and infrastructure that facilitate ongoing developments required for CERN-ISOLDE. A dedicated off-line laboratory (Offline 2) has been recently equipped with a laser setup required for developments of specialized laser ion source types such as VADLIS and LIST. Moreover, it hosts a twin setup of the ISOLDE RFQ cooler and buncher (ISCOOL), which is envisaged to be used for studies of molecular beam creation and breakup as well as the development of the RFQ itself. For material development, especially for nano-structured materials, the new nano laboratory has just been commissioned and will enable to produce and develop nano actinide targets for ISOLDE.
In this contribution we shall describe the infrastructure required for target and ion source developments, highlight recent efforts and experimental results on both target material development and ion source development and we will give an outlook what to expect in the near future.

Speaker: Sebastian Rothe (CERN)
• 30
Low Energy Radioactive Ion Beams at SPES for nuclear physics and medical applications

Around the world, many facilities producing Radioactive Ion Beams (RIBs) using the
Isotope Separation On Line (ISOL) technique have been or are under construction. Among
others, SPES (Selective Production of Exotic Species) is the facility in the installation phase
in these years in the Laboratori Nazionali di Legnaro (LNL). In this type of facility, the
radioactive atoms are produced using a 40 MeV-200 μA proton beam impinging the
Uranium Carbide (UCx) target composed by seven disks in order to dissipate the 8 kW beam
power. The fission products, in the order of 10^13 atoms/seconds, diffuse and effuse out of
the target up to the ion source where are ionized and accelerated by an extraction voltage up
to 40 kV. The formed RIB will be subsequently directed and focalized using different
electromagnetic systems and purified in order to have a pure isotope beam without
contaminants. The RIBs can be sent directly to the low energy experimental area and,
afterwards, to the post-acceleration stage.
Currently the installation program concerning the RIB source provides the set-up of the
apparatus around the production bunker. The main objective is to provide in the next years,
the first low-energy radioactive beams for beta decay experiments using the b-DS (beta
Decay Station) set-up and for radiopharmaceutical applications by means of the IRIS
(ISOLPHARM Radioactive Implantation Station) apparatus. The goal of the ISOLPHARM
project is to provide a feasibility study for an innovative technology for the production of
precursors.
In this presentation, all the specific issues related to the SPES RIB and the Low Energy
beam lines will be appropriately presented and commented, showing the results obtained in
the last years. The main RIB systems, such as ion source systems, target-handling devices
and the installation of low energy transport line, will be presented in detail.

Speaker: Alberto Andrighetto (INFN Laboratori di Legnaro)
• 31
Developments for actinide molecular ion beams at CERN-ISOLDE

The ISOLDE facility at CERN provides experiments with a wide range of isotopes across the nuclear chart, produced in reactions from 1.4 GeV protons with thick targets. The reaction products are typically delivered in the form of charged atomic ions, but molecular species can also be extracted. The development of molecular beams is motivated by improvements to beam extraction and purity as well as interest in studying the radioactive molecules themselves.

Molecules have been studied as a method to efficiently deliver beams of release-limited elements by forming and extracting volatile molecules [1,2] of otherwise refractory species such as carbon [3], boron [4] or refractory metals [5]. Additionally, delivering isotopes on a molecular sideband shifts the mass of interest, and can therefore be used as a technique to improve beam purity by changing the isobaric contamination situation. Beyond their use for enhanced extraction, molecules provide additional opportunities to search for fundamental symmetry violations and contribute to the development of new physics beyond the standard model [6,7]. Recent studies of radium fluoride at ISOLDE [8] demonstrate the experimental capabilities to study beams of radioactive molecules produced at radioactive ion beam facilities and further motivate the development of radioactive molecules.

We will present the first results of ongoing work on molecular ion beams of heavy elements at ISOLDE. Uranium carbide targets were used to produce molecular beams via injection of reactive tetrafluoro methane (CF$_4$) gas. The ion beam composition was studied using: the ISOLTRAP Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF MS) [9] for identification by ToF mass measurements, online γ-ray spectroscopy at the ISOLDE tape station [10,11], and off-line $\alpha$- and γ-ray spectrometry of ion-implanted samples. The results contribute to beam developments for actinide elements and radioactive molecules for fundamental physics research.

References

[1] R. Eder et al., Nucl. Inst. and Meth. B 62, 535 (1992)
[2] R. Kirchner, Nucl. Inst. and Meth. B 126, 135 (1997)
[3] H. Frånberg et al., Rev. Sci. Inst. 77, 03A708 (2006)
[4] J. Ballof et al., Eur. Phys. J. A 55, 65 (2019)
[5] U. Köster et al., Eur. Phys. J. Special Topics 150, 293 (2007)
[6] M. Safronova et al., Rev. Mod. Phys. 90, 025008 (2018)
[7] N. Hutzler et al., arXiv, DOI 10.48550/ARXIV.2010.08709 (2020)
[8] R. Garcia-Ruiz et al., Nature 581, 396 (2020)
[9] R. N. Wolf et al., Int. J. Mass Spec. 123, 349 (2013)
[10] C. Neacşu et al., Nucl. Inst. and Meth. A 1026, 166213 (2022)
[11] R. Catherall et al., J. Phys. G : Nucl. Part. Phys., 44, 094002 (2017)

Speaker: Mia Au (CERN)
• 32
Radioactive ion beam production yields using 1.4- and 1.7-GeV protons at CERN-ISOLDE

CERN-ISOLDE is among the world-leading isotope separation on-line (ISOL) facilities providing radioactive-ion beams (RIBs) for research. ISOLDE's versatility is driven by a 1.4-GeV proton beam delivered by the Proton Synchrotron Booster and its target and ion source repertoire. While more than 1000 isotopes from 76 different elements have been produced at CERN-ISOLDE, user interest often focuses on exotic RIBs that are challenging due to low production and/or low release efficiency from the target-ion source system. As a result, target and ion source developments and facility upgrades for higher quality beams at CERN-ISOLDE are needed to increase the facility's capability. Experimental data shows that by increasing the proton energy, gains in production can be achieved in several regions of the nuclear chart. To validate the expected gain of such an upgrade, a campaign to measure and compare RIB yields using 1.4- and 1.7-GeV protons was recently launched at CERN-ISOLDE. In this contribution we will present the status of this campaign, highlight first experimental results and compare them to theoretical predictions.

Speaker: Simon Stegemann (CERN)
• Coffee Break S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Session 10 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 33
Recent highlights from laser spectroscopy at COLLAPS-CERN
Speaker: Prof. Liss Vazquez Rodriguez
• 34
RAPTOR – a novel approach for high-resolution laser-resonance ionization spectroscopy of radioactive elements

The Resonance ionization spectroscopy And Purification Traps for Optimized spectroscopy (RAPTOR) project is a new experimental setup located at the Ion Guide Separator On-Line (IGISOL) laboratory in the Department of Physics of the University of Jyväskylä. RAPTOR combines the two most common methods for laser spectroscopy in use at radioactive ion beam facilities: collinear laser spectroscopy and in-source laser-resonance ionization spectroscopy, resulting in perhaps the most promising approach for optical spectroscopy by exploiting the high selectivity of resonance laser ionization, the high efficiency of ion detection, and the high resolution permitted using fast beams. This technique, collinear resonance ionization spectroscopy (CRIS) [1], was pioneered in the past decade at the Isotope Separator On-Line Device (ISOLDE) at the European Organization for Nuclear Research (CERN).

While the conventional collinear laser spectroscopy and CRIS methods exploit the kinematic compression of Doppler-broadening effects with beam energies of 30-60 keV, the RAPTOR device uniquely employs beam energies of only a few keV. Although the lower beam energy leads to somewhat lower spectral resolution, it allows for the improvement of the charge-exchange efficiency in the neutralization process, as the probability to neutralize into a specific atomic state increases when the beam energy decreases, also increasing the selectivity of the process. Measurements requiring high efficiency, for example the short-lived bismuth isotopes, are thus uniquely suitable for RAPTOR as the energy of the ions can be optimized to suit the optimum charge-exchange requirements and enables the study of many outstanding physics cases using exotic isotopes that are challenging to produce with traditional ISOL-type facilities.

My contribution will present the technical details and planned upgrades of the RAPTOR device. Recent results from ongoing commissioning tests, such like first RIS spectra from stable copper and ion beam transport simulations will also be presented.

References
[1] A. R. Vernon, et al. “Optimising the Collinear Resonance Ionization Spectroscopy (CRIS) Experiment at CERN-ISOLDE.” Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms, vol. 463, 2020, pp. 384–389.

Speaker: Sonja Kujanpää (University of Jyväskylä)
• 35
Looking for CP violation in nuclear beta decay: First data-taking of the MORA experiment at JYFL, Finland

The MORA project focuses on ion manipulation in traps and laser orientation methods for the searches for New Physics (NP) in nuclear beta decay, looking for possible hints to explain the matter-antimatter asymmetry observed in the Universe. The JYFL Accelerator Laboratory and more specifically the IGISOL facility provide an ideal environment for the initial phase of the MORA experiment. The precise measurement of the so-called triple D correlation is sensitive to Time reversal violation, and via the CPT theorem, to CP violation. The D correlation parameter is particularly sensitive to the existence of Leptoquarks, which are hypothetical gauge bosons appearing in the first theories of baryogenesis. Leptoquarks are now actively searched for at the LHC, the measurements from which provide competitive and complementary constraints. MORA will use an innovative in-trap laser polarization technique for the precision measurement of the D correlation in the beta decay of 23Mg.

In this regard, the first test experiment with a 23Mg beam has been carried out in the IGISOL facility in Feb 2022. For the initial offline optimization, 23Na+ ions slowed down to 100 eV from the RF cooler buncher could be efficiently tuned for trapping. For 500 ms trapping time, efficiencies of 5 to 50% were achieved. During the beam time, a significant amount of 23Mg could be produced; 105 ions per µA of the primary proton beam. A 90 mW circularly polarized laser beam could be injected and aligned in the trap. Despite these achievements, a large contamination of 23Na and a high RF noise on the recoil ion detectors hindered the recording of β-recoil coincidences.

The next experiment will be performed at the end of May 2022 addressing these issues. New target heads and ion guides have already been prepared to remove the sodium contamination and a new RF generator has been employed to suppress the unwanted high order harmonics. After reducing the contamination of 23Na, we should be able to assess the performance of the innovative in-trap laser polarization technique. Along with the whole description of the project, I will be discussing the proof-of-principle measurement and progresses of the MORA experiment.

Speaker: Abhilasha SINGH (GANIL)
• 12:10 PM
Lunch (RAON Tour) S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 2:30 PM
Excursion (Gongjusanseong Fortress) S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Thursday, October 6
• Session 11 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 36
Ion catchers for short-lived isotope research: Challenges, concepts and applications
Speaker: Prof. Timo Dickel
• 37
Gas stopping techniques with reacceleration

Gas stopping of rare isotope beams together with reacceleration is unique at the Facility for Rare Isotope Beams (FRIB) at the Michigan State University. The stopping techniques, with beam manipulation at very low energies, are important developments aimed to slow down fast beams for either use in stopped beam experimental devices or to be injected in the reaccelerator for experiments at energies from 0.3 MeV/u to 12 MeV/u depending on the Q/A of the ion. We developed innovative stopped beam systems that were designed to optimize the stopping and extraction efficiencies for various atomic number ranges, as well as to reduce contamination and increase extraction speed. Moreover, reacceleration of those beams involve techniques of cooling, bunching, charge breeding and acceleration by a state-of-the-art superconducting LINAC (ReA). In this contribution I’ll show the latest results of various gas stoppers and techniques to eliminate contaminants after reacceleration by the ReA. Typical efficiencies of each step will be presented as well as plans for future developments.
This material is based upon work supported by NSF under grant PHY15-65546, and DOE-SC under award number DE-SC0000661

Speaker: Antonio C.C. Villari (FRIB)
• 38
Development of the new helium gas catcher and nuclear mass measurements with the new MRTOF-MS behind the ZeroDegree spectrometer at RIKEN BigRIPS

A new helium gas catcher has been developed at the SLOWRI facility at RIKEN/RIBF aiming at the efficient conversion of the high-energy exotic RI beams from the BigRIPS separator to slow RI beams. The RI beams of relativistic energies are caught and thermalized in a cryogenic helium-gas filled chamber, and the thermalized ions are extracted by an RF ion guide system. The gas catcher has been combined with a multi-reflection time-of-flight mass spectrograph (MRTOF-MS), where atomic masses transported from the gas catcher can be measured with a precision of dm/m < 10$^{-7}$ [1,2].

The gas catcher consists of a two-stage RF carpet (RFCs), where the 1st stage adopts the RF-DC method [3] while the 2nd stage employs the “ion-surfing” method [4]. Initial offline transport tests have been performed using ions from surface ionizers (like Cs and K) by measuring ion currents with Faraday cups. After the gas catcher was combined with the MRTOF-MS apparatus and mass-selective ion counting was enabled, we moved to offline tests using stable ions produced in the He gas by the alpha-ray radiation and radioactive fission products from a $^{248}$Cm source. Using the two different ways of testing, a reasonable performance of the gas catcher for upcoming online experiments was confirmed.

The first online commissioning run was conducted in the end of 2020 downstream of the ZeroDegree spectrometer using parasitic beams from in-beam gamma-ray experiments by the HiCARI campaign. We successfully measured more than 70 atomic masses during the commissioning. A new optimization has been implemented in 2021, which resulted in mass spectra with a mass resolving power on the order of 106 within a total time-of-flight of only 12.5 ms. We further expand the scope of our operations including decay correlated mass spectroscopy and efficient background reduction by in-MRTOF mass selection.

The status of our gas catcher development, a further improvement, new mass measurement results, and the capabilities of our setup will be discussed in this contribution.

[1] M. Rosenbusch et al., Nucl. Intrum. Methods Phys. Res. B 463, 184 (2019).
[2] M. Rosenbusch et al., arXiv:2110.11507 (2021).
[3] M. Wada et al., Nucl. Instr. Methods Phys. Res. B 204, 570 (2003).
[4] G. Bollen, Int. J. Mass Spectrom. 299, 131 (2011).

Speaker: Dr Aiko Takamine (RIKEN Nishina Center)
• 10:20 AM
Photo S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• Coffee Break S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• Session 12 S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• 39
Multi-reflection time-of-flight mass spectroscopy of superheavy nuclides

The KEK Wako Nuclear Science Center operates the KEK Isotope Separation System (KISS) which utilizes a small gas stopping cell to produce low-energy beams of multi-nucleon transfer (MNT) products. The group also co-manages, with the RIKEN SLOWRI Team, gas cells and multi-reflection time-of-flight mass spectrographs (MRTOF) at both the end of the ZeroDegree line of BigRIPS and following the GARIS-II recoil separator; a new system is presently under construction for use with the GARIS-III recoil separator. At KISS and the GARIS facilities, one of the primary interests are transuranium nuclides. For understanding both the general physics of superheavy nuclides and the role that fission-recycling of transuranium nuclides has on the astrophysical r-process, measurements of the masses and half-lives of these nuclides would be invaluable. To perform such measurements, which often involve extremely low production yields, we have been developing ion detectors for use with multi-reflection time-of-flight mass spectrographs which allow for ToF-decay correlated measurements. In the case of beta-decay, this technique can suppress signals from stable molecular ions while for alpha-decay it can provide a clear identification of radioactive ions. Both decays allow for the simultaneous determination of atomic mass and decay half-life in a single measurement. The future addition of a capability to measure x-rays and gamma rays will further expand our ability to probe these most exotic of nuclei.
Recent results and future plans for these devices will be presented.

Speaker: Peter Schury (KEK Wako Nuclear Science Center)
• 40
Uncovering the Proton Drip-Line of Tm with TITAN's MR-TOF Mass Spectrometer

The change in nuclear binding energy associated with a nuclear decay or reaction can be determined directly using nuclear mass measurements. Precision mass spectrometry techniques, such as the Multiple-Reflection Time-of-Flight technique (MRTOF), are therefore indispensable tools for characterizing the strength of nuclear binding.

In the vicinity of the neutron-deficient limits of the N=82 shell closure, nuclear half-lives are sufficiently long to allow for high-precision mass measurements up to, and even across the proton drip-line. This provides a testbed for theoretical predictions of its location. Radioactive beam experiments were performed to establish the precise location of the proton drip-line in the Tm isotopic chain. This was achieved by obtaining previously unmeasued Tm masses, as well as by updating an anomalous mass contained within the 2020 Atomic Mass Evaluation.

These measurements utilized beams of radioactive isotopes produced at TRIUMF's Isotope Separator And Accelerator (ISAC), a well-established ISOL facility. ISAC delivered high-intensity beams to the MRTOF at TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN), where they were measured to precisions on the order of $\frac{\delta m}{m} \approx 10^{-7}$. Measurements of the rarest species were made possible by employing the recently implemented isobaric retrapping technique within the MRTOF to suppress contaminant species in the radioactive beam.

Speaker: Brian Kootte (TRIUMF/University of Manitoba)
• 41
Development of neutron detection systems at the NDPS of RAON

Nuclear Data Production System (NDPS) at RAON has been built to produce nuclear data mainly generated by the reactions induced by neutrons of tens of MeV. For the neutron Time-Of-Flight (TOF) measurement, neutron monitoring detectors based on a gas-filled Parallel Plate Avalanche Counter (PPAC) and a MICRO-MEsh-GASeous (MICROMEGAS) detector have been developed by the Rare Isotope Science Project (RISP) and Sungkyunkwan University (SKKU). These detectors have a neutron converter with a thin $^{232}$Th layer, which produces fission products due to fast neutrons. The PPAC achieved a 1 ns FWHM time resolution in a test with a $^{241}$Am α source and also showed good performance when tested with fast neutrons generated by a 45 MeV proton beam through the $^{9}$Be(p, n)$^{9}$B reaction. Additionally, EJ-301 liquid scintillation detectors will be used for the measurement of neutron flux with pulse shape discrimination capability. Slow charge signals as well as fast timing signals from the detectors will be processed for particle identification by a data acquisition(DAQ) system, located at a separate control room through 30 m long cables. Development of the detection system and the test results will be reported with on-site assembly status.

Speaker: Dr Kwang Bok Lee (RISP)
• 42
Status of LAMPS at RAON

A new radioactive ion-beam accelerator facility, RAON, is under construction in Korea. Among the various experimental systems, the Large Acceptance Multi-Purpose Spectrometer (LAMPS) will be available in the high-energy experimental hall at RAON. The main goal of the LAMPS system is to investigate the nuclear equation of state (EoS) and, especially, the symmetry energy (SE) of the compressed nuclear matter, which should be essential to understand the effective nuclear interactions and structure of the astrophysical objects like neutron stars.
In this presentation, the status of the development and construction of the basic version of the LAMPS system will be presented. The components of the basic LAMPS system consist of the beam diagnostic elements, such as the Starting Counters (SC) and Beam Drift Chambers (BDC), the Time-Projection Chamber (TPC), the Barrel and Forward Time-of-Flight system (BTOF and FTOF), the forward neutron detector array (NDA), and the superconducting solenoid magnet. The overview of the present status for each detector components will be given with some prospects.

Speaker: Byungsik Hong (Korea University)
• 12:30 PM
Lunch S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• Session 13 S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• 43
The PUMA experiment at CERN

The main goal of the PUMA (antiProton Unstable Matter Annihilation) experiment is to use antiprotons as a tool to investigate properties of exotic nuclei. For this, antiprotons produced at the AD/CERN and decelerated by the ELENA storage ring will be captured, cooled and transported to the ISODLE facility where the antiprotons will be mixed with short lived isotopes. During this process, an antiproton can be captured by the nucleus and will subsequently annihilate with a neutron or a proton at the surface of the nucleus itself. The fingerprint of this annihilation will be measured using a time-projection-chamber. With this knowledge of the ratio of protons to neutrons on the outermost part of the nuclei distribution, phenomena like a neutron or a proton halo or neutron or proton skins can be investigated.
This contribution will give an overview of the PUMA experiment, present its status and highlight some of the main physics goals

• 44
Nuclear physics with TriSol at Notre Dame’s Nuclear Science Laboratory

The detailed study of radioactive nuclei has resulted in opportunities for addressing many open questions in nuclear structure and nuclear astrophysics. For over three decades, the TwinSol separator at the University of Notre Dame has produced high-quality in-flight radioactive beams at low-energy for light isotopes that have been used in experiments aimed at nuclear structure, astrophysics, and fundamental symmetries studies. We have recently upgraded the TwinSol separator by adding additional elements: a dipole magnet, and a third solenoid. This new TriSol separator will improve the quality and purity of future radioactive beams. This improvement will enable the use of heavier beams and address beam contamination that has hindered past experiments. The current status of TriSol and its science program will be presented along with the role the TriSol program plays in the current landscape of nuclear physics user facilities. The TriSol program includes plans for the study of $^{11}$C($p$,$p$)$^{11}$C reactions for investigating the nature of the first stars, $^{14}$O($\alpha$,$p$)$^{17}$F and its influence on reaction networks in x-ray bursts, the measurement of fusion reactions on Ne isotopes, and precision half-life measurements for fundamental symmetries studies.

Speaker: Prof. Tan Ahn (University of Notre Dame)
• 45
Large-acceptance isotope identification array FAZIA: Status and R&D activities for upgrade

The FAZIA apparatus is a multi-detector array designed to identify a wide range of charge and mass of reaction products in heavy-ion collisions in the Fermi energy domain. The basic module of FAZIA is the block, consisting of 16 three-layer telescopes. The first two layers are highly homogeneously doped Si detectors with the thickness of 300 μm and 500 μm, respectively, and the third layer is a 10 cm thick CsI(Tl) scintillator read out by a photodiode. The detector signals are extracted in real-time based on the digital signal processing implemented on the FPGAs. The recent experiments demonstrated that the charge could be discriminated up to more than Z=54 using the ΔE-E technique and the pulse shape analysis. In addition, the isotopic discrimination has been achieved up to Z ~ 25 with the ΔE-E technique and up to Z ~ 20 with the pulse shape analysis in the silicon layer. Recently, there have been activities for the FAZIA detector upgrade to use thicker and thinner silicon layers for enlarging the kinematic coverage. In addition, the R&D is in progress to make the front-end electronics board more compact and versatile. In this talk, we present the current status of the FAZIA detector and some highlights of the R&D activities for the upgrade.

Speaker: MinJung Kweon (Inha University)
• Coffee Break S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• Session 14 S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• 46
OEDO-SHARAQ system: multifaceted performances in low-energy RI production and high-resolution spectroscopy

The OEDO-SHARAQ system is the world's first beamline characterized by the energy-degrading of RI beams. While this system also has high performance on high-resolution nuclear spectroscopy with RI beams.
A minor update of the system, performed in 2021, provided multifaceted improvements to the system in both effective energy-degrading and high-resolution spectroscopy with RI beams.
We report the achievements of OEDO-SHARAQ system in experimental studies implemented recently and introduce perspectives about upcoming physics programs of OEDO-SHARAQ.

Speaker: Shin'ichiro Michimasa (Center for Nuclear Study, The University of Tokyo)
• 47
A multi-purpose experimental instrument KoBRA for low-energy nuclear physics at RAON

A multi-purpose experimental instrument, named as KoBRA (Korea Broad acceptance Recoil spectrometer and Apparatus), has been constructed for low-energy nuclear physics experiments at RAON (Rare Isotope Accelerator complex for ON-line experiments) in Korea. KoBRA will be utilized to produce rare isotope beams at an energy range of about 5 - 20 MeV/nucleon in early-phase experiments. A test was performed to measure the positions of 4He ions at the dispersive and achromatic focuses of KoBRA, using an 241Am α-source placed at the production target position. The position distributions of 4He ions are nearly consistent with the results of Monte Carlo calculation. The detailed design including ion optics and present status of KoBRA are described, together with the status of detectors for beam diagnostics and particle identification of rare isotopes.

Speaker: Kyoungho Tshoo (RISP/IBS)
• 48
Commissioning of the DESIR High-Resolution mass Separator

DESIR is the low-energy part of the SPIRAL2 ISOL facility in the final design
at GANIL. The High-Resolution mass Separator (HRS) included in DESIR is a
180◦ symmetric online separator with two 90◦ magnetic dipole sections arranged
with electrostatic quadrupoles, sextupoles and a multipole on the mid plane.
The HRS is now completely mounted at LP2IB/CENBG and under commissioning
for the next years before its transfer at the entrance of the DESIR facility.
Optical aberrations, mainly introduced by the dipoles, must be corrected up to
the highest order to guarantee an optimal resolution of the separator. They are
measured with a pepperpot-type emittance-meter, analysed then corrected with
the 48-poles electrostatic multipole.
Up to now, 2nd order (hexapolar) and part of 3rd order (octupolar) aberrations
are under control and an optimal FWHM separation has been achieved for two
beams with ΔE/E = ΔM/M = 1/25000.
We will present the effects of optical aberrations on the beam and its emittance
figure, as well as the effect of the associated corrections with the multipole.
Finally, we will show the latest resolution measurements and associated methodology.

Speaker: Julien Michaud (LP2IB(CENBG) - CNRS)
• 49
Little-known ways to apply nuclear physics techniques to chemistry and medicine

As humans, we are a mixture of diverse chemical elements, a fragile composition that hangs in an improbable yet finely tuned balance. If this is disturbed, either due to a deficiency or excess of certain elements, it can lead to pathologies which have been linked to severe diseases such as cancer, Alzheimer’s disease, or Parkinson’s disease. For many metals in our body, such as Mg, Zn and Cu, the absence of convenient physical and spectroscopic properties with which to study them has held back a detailed understanding of their role in health and disease.

Nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for studying the structure and dynamics of metal-binding biomolecules in solution. In practice, however, NMR suffers from poor sensitivity for several elements. Beta-radiation detected NMR (β-NMR) spectroscopy is a lesser-known analogue of NMR which requires radioactive isotopes rather than stable ones, offers a billion-fold is based on the detection of beta-particles emitted anisotropically by spin polarized nuclei. The combination of nuclear spin polarization and high detection efficiency of beta-particles gives rise to a billion-fold or higher increase in sensitivity, and it allows for interrogation of elements which are otherwise difficult to access.

In this presentation, I will demonstrate the potential of the β-NMR technique and highlight recent β-NMR experiments with biomolecules in solutions.

Speaker: Prof. Monika Stachura
• 50
Optimal reaction energy for synthesis of element 119 via 51V+248Cm reaction probed by quasielastic barrier distribution measurement

The periodic table is now completely filled up to the seventh period. The synthesis of elements 119 and 120 has been attempted in several cases using the combination of actinide targets and projectile beams heavier than $^{48}$Ca. However, these new elements have not been discovered yet so far [1-4].
In the synthesis of superheavy elements, the reaction energy is the most important parameter that significantly affects the experimental efficiency. At RIKEN, element 119 is being searched using a $^{51}$V+$^{248}$Cm hot fusion reaction. The optimal reaction energy of this reaction system is unknown since theoretical predictions vary widely.
Under these circumstances, our group has developed a method to estimate the optimal energy from the quasielastic (QE) barrier distribution [5,6]. From the systematic studies of the relation between the QE barrier distribution and the fusion-evaporation cross section $\sigma_\mathrm{ER}$ for the hot-fusion reaction systems with an actinide target, the optimal reaction energy for maximizing $\sigma_\mathrm{ER}$ was found to be slightly larger than the average Coulomb barrier height $B_0$ obtained from the QE barrier distribution [6]. Furthermore, it was also pointed out that the side-collision energy $B_\mathrm{side}$, which leads to a compact configuration of the colliding nuclei by touching along the short axis of the prolately-deformed target nucleus, deduced from the experimental $B_0$ value, is in good agreement with the optimal energy of the experimental $\sigma_\mathrm{ER}$ [6].
In our latest study [7], we measured the QE barrier distribution of $^{51}$V+$^{248}$Cm, using a gas-filled recoil ion separator GARIS-III at a recently upgraded Superconducting RIKEN Heavy Ion LINAC (SRILAC) facility. The energy corresponding to the $B_\mathrm{side}$ was derived from the $B_0$ value determined from the present experiment, and the optimal reaction energy was estimated based almost purely on experimental evidence. Using the optimal energy obtained in this study, an experiment to synthesize element 119 is currently in progress at RIKEN.
REFERENCES
[1] Yu. Ts. Oganessian et al., Phys. Rev. C 79 (2009) 024603.
[2] S. Hofmann et al., GSI Report 2008 (2009) 131.
[3] S. Hofmann et al., Eur. Phys. J. A 52 (2016) 180.
[4] J. Khuyagbaatar et al., Phys. Phys. C 102 (2020) 064602.
[5] T. Tanaka et al., J. Phys. Soc. Jpn 87 (2018) 014201.
[6] T. Tanaka et al., Phys. Rev. Lett. 124 (2020) 052502.
[7] M. Tanaka et al. for nSHE collaboration, submitted.

Speaker: Masaomi Tanaka (RIKEN Nishina Center)
• 5:30 PM
Poster Award / IAC Announce S236

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• 6:00 PM
Banquet S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• Friday, October 7
• Session 15 S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• 51
Laser Spectroscopy of the Heaviest Elements at SHIP at GSI

Laser spectroscopy is a versatile tool to unveil fundamental atomic properties of an element and information on the atomic nucleus. Up to the chemical element fermium (Z=100), a limited number of long-lived isotopes can be produced in macroscopic amounts through irradiation of actinide samples in reactors where they undergo neutron capture and successive beta decay. Heavier elements and more exotic isotopes of the lighter elements are only accessible through fusion-evaporation reactions at minute quantities and at high energies, hampering their study by optical spectroscopy. However, the heaviest elements are of particular interest as their electron shell is strongly influenced by electron-electron correlations and relativistic effects changing the electron configuration and thus, the chemical behavior [1,2]. Furthermore, subtle changes in the atomic transition for different isotopes of the same element allow fundamental nuclear information to be inferred.
An exploration of the region of the heaviest elements with laser spectroscopy became possible with the RAdiation Detected Resonance Ionization Spectroscopy (RADRIS) technique. Here, recoils from fusion-evaporation reactions, which were transmitted by the velocity filter SHIP at GSI Darmstadt, are stopped in high-purity argon gas and collected onto a thin filament. After re-evaporation, the released neutral atoms are probed by two-step resonance laser ionization. The so created photo-ions were then guided to a detector where they were identified by their characteristic alpha decay. After the first identification and characterization of a strong atomic ground-state transition in $^{254}$No [3] detailed studies on further nobelium isotopes were performed [4].
Here, we will present advancements and recent results of the RADRIS technique along with future prospects for laser spectroscopy of the heaviest elements. This includes the application on decay-daughter products of nobelium enabling the study of the fermium isotopes $^{248-250}$Fm, and with a dedicated detector setup also the long-lived isotope $^{254}$Fm ($T_{1/2}$=3.24 h). The setup’s performance was furthermore optimized with respect to the filament increasing the total efficiency for the search of atomic levels in heavier elements such as lawrencium (Z=103). A first experimental campaign for the search of an atomic level in $^{255}$Lr was recently performed.
Next steps include the extension of the RADRIS method to more exotic isotopes and the continuation of the level search in lawrencium (Z=103) as well as developments for higher spectral resolution spectroscopy. For the latter a dedicated setup was recently commissioned combining the efficient stopping and neutralization from the RADRIS technique with the high resolution of in-gas-jet spectroscopy [5,6]. Laser spectroscopy in the low-density and low-temperature regime of the jet enables higher resolution in the spectroscopy while the continuous operation and swift evacuation of the gas cell using electrical fields will allow us to address shorter-lived isotopes and isomers as, e.g., the lower lying 266 ms K-isomer in $^{254}$No.

1. E. Eliav, S. Fritzsche, U. Kaldor, Nucl. Phys. A 944, 518 (2015).
2. P. Schwerdtfeger, et al., Nucl. Phys. A 944, 551 (2015).
3. M. Laatiaoui, et al., Nature 538, 495 (2016).
4. S.Raeder et al. Phys. Rev. Lett. 120.23, 232503 (2018).
5. Kudryavtsev, Yu, et al. Nucl. Instrum. Meth. Res. B 297, 7-22 (2013)
6. S. Raeder et al., Nucl. Instrum. Meth. Res. B, 463, 272-276. 272-276, (2020).
Speaker: Sebastian Raeder (GSI Helmholtzzentrum für Schwerionenforschung GmbH)
• 52
Progress towards the EDM3 instrument at FRIB: A tool for studying radioactive molecules embedded inside cryogenic solids

The Facility for Rare Isotope Beams (FRIB) at Michigan State University has recently commenced operation and delivered first radioactive ion beams to its users [1, 2]. Besides its portfolio of fast, stopped, and re-accelerated beams, isotope-harvesting techniques are being developed to exploit isotopes that are otherwise lost to the beam dump [3]. The study of radioactive molecules receives increasing attention due to their enhanced sensitivity to fundamental symmetry violations and Beyond Standard Model physics [4].

In this contribution, we introduce the FRIB-EDM3-instrument which is currently under construction. The setup was designed to study polar radioactive molecules (like RaF) in transparent cryogenic solids by laser spectroscopy with the EDM3-method [5]. The efficient ionization of harvested radioisotopes from aqueous phase is pursued with a spray-ionization method [6]. Subsequently, the molecular ion beam is analyzed by mass-to-charge ratio by a quadrupole mass filter and neutralized in a charge-exchange cell before its implantation in a solid argon matrix. We will present the design of the instrument and report on the progress of its construction.

References
[1] J. Wei et al., International Journal of Modern Physics E 28, 1930003 (2019)
[2] https://frib.msu.edu/news/2022/frib-ribbon-cutting.html
[3] E.P. Abel et al., J. Phys. G: Nucl. Part. Phys. 46, 100501 (2019)
[4] N.R. Hutzler et al. (2020), 10.48550/ARXIV.2010.08709
[5] A.C. Vutha et al. (2018), 10.48550/ARXIV.1806.06774
[6] R.T. Kelly et al., Mass Spectrometry Reviews 29, 294 (2010)

Speaker: Jochen Ballof (Facility for Rare Isotope Beams (FRIB))
• 53
Status of the JetRIS apparatus for laser spectroscopy of the heaviest elements

Laser spectroscopy measurements can provide information about fundamental properties of both atomic and nuclear structure. These measurements are of particular importance for the heaviest actinides and superheavy elements, where data are sparse. Recent resonance-ionization-spectroscopy experiments at GSI, Darmstadt, Germany, have focused on in-gas-cell measurements using the RADRIS technique [1,2], successfully measuring a strong ground-state transition in ${}^{252-254}$No [3]. However, the limited spectral resolution of these measurements hampers the precision, and eventually renders determining the nuclear moments and spins impossible. Furthermore, the subsequent collection and measurement cycle limits accessible isotopes to those with lifetime of at least about 1 s. To overcome these limitations, a new JetRIS apparatus has been constructed to perform laser spectroscopy of atoms in a hypersonic jet [4]. In JetRIS, the highly energetic recoil ions are slowed down in argon gas and guided by electric fields to a heated filament for neutralization. They are then extracted by the gas into a hypersonic gas jet. This gas jet provides a low-density and low-temperature environment, which will improve the spectral resolution by about an order of magnitude to hundreds of MHz [5]. In addition, it allows the continuous operation for fast extraction, giving access to short-lived nuclei.
In the near future a narrow-bandwidth and high-repetition-rate titanium:sapphire laser system will be added to the existing state-of-the-art, narrow-bandwidth dye laser system. This combination will ensure complete versatility and highest performance [6]. The setup was recently commissioned at the GSI within the FAIR phase-0 program. The obtained performance of the apparatus and the accompanying laser system will be discussed along with the future perspectives in the talk.

1 H. Backe, et al., Nucl. Phys. A 944, 492 (2015).
2 F. Lautenschläger, et al., Nucl. Instrum. Methods Phys. Res. Sect. B 383, 115 (2016).
3 M. Laatiaoui, et al., Nature 538, 495 (2016).
4 S. Raeder, et al., Nucl. Instrum. Meth. Res. B, 463, 272-276 (2020).
5 R. Ferrer, et al., Nat. Commun. 8, 14520 (2017).
6 S. Raeder, et al., Nucl. Instrum. Meth. Res. B 463, 86-95 (2020).

Speaker: Matou Stemmler (JGU Mainz - Institut für Physik)
• 54
Development of the collinear laser spectroscopy system for the study of unstable nuclei at BRIF facility

Collinear laser spectroscopy is a powerful tool for the study of the basic properties, such as the spins, magnetic moment, electric quadrupole moments and charge radii, and the related structure of exotic nuclei far from β-stability line [1]. In order to study these properties of unstable nuclei at Radioactive Ion-beam Facility in China, we have developed a collinear laser spectroscopy (CLS) system, which has been tested by using the stable Ca ion beams produced from a laser ablation ion source [1]. This CLS system has been recently installed at the Beijing Radioactive Ion-beam Facility (BRIF) [2]. The first successful on-line commissioning experiment of this system was performed by measuring the hyperfine structure of stable (39K) and unstable (38K) ion beams, in the continuous mode, produced at BRIF facility. This on-line experiment demonstrates the overall functioning of this CLS system, which opens new opportunities for laser spectroscopy measurement of unstable isotopes at BRIF and other radioactive ion beam facilities in China.

In this talk, the technique details of the CLS setup and the offline/online commissioning experiments, together with the on-going development of the collinear resonance ionization spectroscopy and RFQ cooler buncher, will be presented. The future scientific prospect of the CLS setup at BRIF will be discussed.
[1] P. Campbell, I. Moore, and M. Pearson, Prog. Part. Nucl. Phys. 86 (2016)
[2] Shiwei Bai, X.F. Yang, S.J.Wang et al., Nucl. Sci. Tech.33,9 (2022)
[3] T.J. Zhang, B.Q.Cui, Y.L. Lv. Nucl. Instrum. Methods Phys. Res. B, 463, 123-127 (2020).
[4] S.J.Wang, X.F. Yang, Shiwei Bai et al., Nucl. Instrum. Methods Phys. Res. A, 463, 123-127 (2022).

Speaker: Xiaofei Yang (Peking University)
• Coffee Break S236

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55 EXPO-ro, Yuseong-gu, Daejeon
• Session 16 S236

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• 55
First experimental campaign at the new fragment separator ACCULINNA-2: superheavy 6,7H isotopes elucidated

Recently the extremely neutron-rich systems 7H, 6H were studied in the direct 2H(8He, 3He)7H and 2H(8He, 4He)6H transfer reactions [1-3] with a 26 AMeV secondary 8He beam produced at the new ACCULINNA-2 fragment separator [4]. The missing mass spectra and center-of-mass angular distributions of 7H(6H), as well as the momentum distributions of the 3H fragment in the 7H(6H) frame, were reconstructed.

A solid experimental evidence is provided that the resonant states of 7H are located in its spectrum at 2.2(5) and 5.5(3) relative to the 3H+4n decay threshold. Also, there are indications that the resonant states at 7.5(3) and 11.0(3) MeV are present in the measured 7H spectrum. Based on the energy and angular distributions obtained for the studied 2H(8He, 3He)7H reaction, the weakly populated 2.2(5)-MeV peak is ascribed to the 7H ground state (g.s.). It is highly plausible that the firmly ascertained 5.5(3)-MeV state is the 5/2+ member of the 7H excitation 5/2+ – 3/2+ doublet, built on the 2+ configuration of valence neutrons. The supposed 7.5-MeV state can be another member of this doublet.

The measured missing mass spectrum of 6H shows a broad bump at ∼ 4 − 8 MeV above the 3H+3n decay threshold. This bump can be interpreted as a broad resonant state at 6.8(5) MeV. The obtained spectrum is practically free of the 6H events below 3.5 MeV (center-of-mass cross section is less than 5 μb/sr in the 5-16 deg. angular range). The steep rise of the 6H missing mass spectrum at ∼ 3 MeV allows to derive the lower limit for the possible resonant-state energy in 6H to be 4.5(3) MeV. According to the paring energy estimates, such a 4.5(3) MeV resonance is a realistic candidate for the 6H g.s.. The obtained results confirm that the decay mechanism of the 7H g.s. is the “true” (or simultaneous) 4n emission. The resonance energy profiles and the momentum distributions of fragments of the sequential 6H→ 5H(g.s.)+n → 3H+3n decay were analyzed by the theoretically-updated direct four-body-decay and sequential-emission mechanisms. The measured momentum distributions of the 3H fragments in the 6H rest frame indicate very strong “dineutron-type” correlations in the 5H ground state decay.

In addition, the proton and deuteron pickup reactions 2H(10Be,3He)9Li and 2H(10Be,4He)8Li were studied for the first time in the same setup with 44 AMeV 10Be radioactive beam. These measurements were motivated as test reactions to control the calibration and resolution over excitation energy for the studied 7H and 6H systems.

[1] A.A. Bezbakh et al., PRL, 124 (2020) 022502.
[2] I.A. Muzalevskii et al., PRC 103 (2021) 044313.
[3] E.Yu. Nikolskii et al., arXiv:2105.04435v6 [nucl-ex].
[4] A.S. Fomichev et al., Eur. Phys. J. A 54, 97 (2018).

Speaker: E.Yu. Nikolskii (NRC "Kurchatov Institute", Moscow, Russia / Flerov Laboratory of Nuclear Reactions, JINR, Dubna, Russia)
• 56
New fast-timing $\gamma$-ray detector system in Korea: KHALA

The lifetimes of excited nuclear states play an important role in nuclear structure. These many-body quantum dynamic information are crucial particularly for understanding the nuclear shell structure. For instance, the excited states of nuclei near magic numbers provide evidence of the changes in shell structure from a single-particle nature to collective nature. Therefore, the measurement of the lifetimes of the excited state may give a perspective on overall features of nucleon interactions and subsequently the shell and shape structure of nuclei.
Recently, exotic rare-isotope beams far off the $\beta$-stability line were available, and the various state-of-the-art detectors and relevant electronics were developed. With such advances in technology, the fast-timing measurement has attracted much attention. The timing measurement requires more sophisticated and difficult technique compared to the energy measurement. A LaBr$_{3}$(Ce) inorganic scintillator is one of the optimal materials for this scientific purpose because of its great light yield and very short time response. For this reason, the construction of the LaBr$_{3}$(Ce) detector system became popular in the field and FATIMA [1] is one of the successful cases.
In Korea, a new fast-timing $\gamma$-ray detector system, Korea High-resolution Array of LABr$_{3}$(Ce) – KHALA, is being developed to measure such a short lifetime which is typically in a range of a few tens of picoseconds to a few nanoseconds. The KHALA is comprised of 36 LaBr$_{3}$(Ce) scintillator detectors with a 1.5-inch diameter and 1.5-inch height crystal size, particularly dedicated for the fast-timing response. In this talk, the development of the KHALA and its performances such as the energy resolution, timing response, and detection efficiency will be introduced in detail. Moreover, future experimental plans will be also discussed.

[1] M. Rudigier et al., Nucl. Inst. and Meth. in Phys. Res. A 969, 163967 (2020).

Speaker: Byul Moon (Center for Exotic Nuclear Studies, Institute for Basic Science)
• 57
Status report of in-flight recoil separators RITU and MARA

The gas-filled in-flight separator RITU at Jyväskylä, Finland, has
been recently re-commissioned. A new focal plane instrumentation has
been constructed and set-up at the RITU focal plane. It shares the
same dimensions with the MARA focal plane which enables the use of
same detectors and vacuum parts in both. Alongside the instrumentation
the RITU recommissioning results and the brief operational principle
will be presented.

The in-flight recoil mass spectrometer MARA has been used successfully
over many years. The main objective has been the study of the neutron
deficient nuclei close to the proton drip line and nuclei around the
N=Z line. Several new isotopes and proton emitters have been
identified in the decay studies at the focal plane and new nuclear
structure information extracted via in-beam studies utilizing MARA and
the Jurogam Ge-detector array. A new scintillator detector, Tuike, has
been taken in use at the focal plane to improve the identification of
weakly produced isospin-multiplet members under study by
detecting high-energy betas. In addition to the brief overview
of these type of MARA experiments, the description of charge plunger set
up, able to probe lifetimes of highly converted transitions in heavy
nuclei, will be given.

Speaker: Juha Uusitalo (University of Jyväskylä)
• 58
KoBRA Wien Filter: Specifications and Project Status

A Wien Filter is one of the key components in ion optics also known as a velocity separator. It consists of a dipole magnet generating a magnetic field, and an electrostatic dipole in the gap of the magnet generating an electric field perpendicular to both the magnetic field and the beam axis. The electric and magnetic fields are properly adjusted to obtain expected ion beams with a certain velocity.

Rare Isotope Accelerator complex for ON-line experiments, RAON, is a new RI beam facility in South Korea nearing completion including Korea Broad acceptance Recoil spectrometer and Apparatus, KoBRA, which will produce low-energy radioactive ion beams. KoBRA has been established and tested with radioactive fission source in 2021, and will be commissioned with an ion beam of ~ 20 MeV/nucleon delivered from RAON. One of the main purpose of KoBRA is to separate and to identify low-energy rare isotopes using products from the nuclear reaction such as multi-nucleon transfer.

Recently, a new project at Center for Exotic Nuclear Studies (CENS) has been launched to introduce a Wien Filter in the KoBRA beamline, and this KoBRA Wien Filter (KWF) will play a significant role to enhance the isotope separation performance in beam production of KoBRA. Its specifications were determined based on the optimal ion optics of KoBRA to produce a low-energy beam, especially, the beams less than about 5 MeV/nucleon suitable for nuclear astrophysics experiments. The project is in the manufacturing phase and we expect that it will be installed within 2023.

In this talk, we will present the current status of KWF development and the details of its specifications as well as the ion optics of KoBRA with KWF. We will also discuss about future plans for the RI beam production and separation in KoBRA.

Speaker: Jongwon Hwang (Center for Exotic Nuclear Studies, Institute for Basic Science)
• 12:20 PM
Lunch S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• Session 17 S236

### S236

#### Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
• 59
New applications of positron-emitting nuclei in medical imaging and treatment at GSI

In comparison to protons, carbon ion radiotherapy (CIRT) offers a promising treatment alternative due to its prominent Bragg peak, reduced lateral scattering, and high linear energy transfer (LET). Due to these characteristics, a higher conformal dose deposition to the tumor volume is possible, while sparing as much healthy tissue as possible. In 1994, the National Institute of Radiologic Sciences (NIRS) in Japan began the first CIRT, at HIMAC in Chiba, followed by Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany, in 1997, and thereafter by other facilities.
One of the major challenges of CIRT is the lack of accuracy in the image guidance systems. This is due to the inherent uncertainties in the conversion from X-ray computer tomography (CT) data to particle stopping powers, ranges, positioning of the patient, and anatomical changes. Uncertainty in the location of dose deposition requires larger safety margins for the tumor in the treatment planning, which results in irradiation of a larger volume of normal tissue. An established technique for the range verification in CIRT is positron-emission tomography (PET) imaging of the positron emitters produced by the fragmentation of the target and projectile. GSI was the first CIRT facility to establish the “online” PET as an online range verification tool in a clinical setting. However, the use of PET for range verification in heavy ion therapy with stable beams has the drawbacks: the mismatch of the activity peak to the Bragg peak of the treatment beam, and the low photon statistics compared to that of a positron emitter. A promising way forward is to use short-lived positron emitters as therapy beams. The technique was pioneered by Lawrence Berkeley National Laboratory and at the early stage of ion-beam therapy investigations at GSI, the scope of the in-beam PET imaging using radioactive ion-beam was investigated. Further developments at HIMAC, Japan, are focused on the positron-emitting isotopes of carbon and oxygen for therapy. To date, the technique has been limited to use as a low-dose probe beam for pre-treatment range verification due to the orders of magnitude lower yield of secondary radioactive ions as compared to the primary beam intensity.
With the recent intensity upgrade of accelerators, the fragment separator FRS at GSI is now capable of delivering secondary beams of short-lived positron emitters with therapy-relevant intensities. Taking advantage of this upgrade, a European initiative on biomedical applications of radioactive beams (BARB) was launched at GSI in 2021, which aims at pre-clinical validation of in-vivo beam visualization and ion-beam therapy with positron-emitting isotopes of carbon and oxygen. As a first step towards this goal, PET imaging studies of high-intensity beams of positron-emitting isotopes of oxygen and carbon at therapy-relevant energies were performed at the symmetric branch of FRS. The secondary beams, with a purity of >98% and intensities of up to 108 ions/sec, were implanted into tissue-equivalent plastic, PMMA, to produce high-quality images with a dual-plane PET scanner. The main aim of this experiment was to explore the possibility of real-time range verification using positron-emitting therapy beams and conventional PET. The results on the impact of ion-optical modes of FRS (e.g., mono-energetic, achromatic) and the beam intensity on PET image quality were investigated.
The goals within the coming years are the full characterization of the dose profiles of high-intensity radioactive ion beams in preparation for pre-clinical studies, the development of a dedicated BARB detector that combines PET and prompt gammas to achieve submillimeter resolution, and the first small animal irradiation with positron-emitting beams. Another major development within the project was the setting up of the beam transport from FRS and the medical cave (cave-M) of GSI where the abovementioned experiments are conducted. The first successful delivery of the fragment beams from FRS to biomedical experiments at cave-M opened up a new application for radioactive ion beams at GSI. An overview of the field and the results from the first year of the BARB project will be presented.
This work is supported by European Research Council (ERC) Advanced Grant 883425 BARB.

Speaker: Sivaji Purushothaman (GSI Helmholtzzentrum für Schwerionenforschung GmbH)
• 60
Characterization and optimization of ISOLDE beams of Dy/Tb isotopes for medical applications

Terbium is unique for medical applications since different Tb isotopes emit $\alpha$, $\beta^-$, $\beta^+$ or $\gamma$-radiation or conversion and Auger electrons respectively. In particular, the quadruplet of Tb isotopes $^{149}$Tb, $^{152}$Tb, $^{155}$Tb and $^{161}$Tb can cover together all diagnostic and therapeutic modalities in nuclear medicine [1]. Their identical chemical and biochemical properties assures fully exchangeable in vivo behavior.

While the neutron-rich $^{161}$Tb is reactor-produced, the neutron-deficient Tb isotopes are accelerator-produced, mainly by (p,x n) reactions on enriched Gd targets or by spallation of Ta targets combined with on-line or off-line isotope separation at CERN-ISOLDE or CERN-MEDICIS respectively [1-5].

Due to the relatively low volatility of trivalent lanthanides, the Ta target and the ionizer line have to be kept at high temperature. Dysprosium is more easily released than terbium, therefore at ISOLDE the collections of Tb isotopes are performed indirectly, by resonantly laser ionizing the Dy precursor isotopes. However, there is considerable background of surface ionized isobars and pseudo-isobars’’ of oxide sidebands. The latter can actually dominate the overall activity and dose rate of collected samples and should be minimized to limit the personal dose during handling, transport and chemical separation of the collected Tb samples.

On-line measurements with the ISOLTRAP multi-reflection time-of-flight mass spectrometer (MR-ToF MS) [6,7] and off-line $\gamma$-ray spectrometry of collected test samples were used to characterize the beam composition at masses 149, 152 and 155 as function of target temperature, ionizer temperature and laser settings respectively.

[1] C. Müller et al., J. Nucl. Med. 53 (2012) 1951.
[2] G.J. Beyer et al., Radiochim. Acta 90 (2002) 247.
[3] R. Formento Cavaier et al., Phys. Procedia 90 (2017) 217.
[4] U. Köster et al., Nucl. Instrum. Meth. B 463 (2020) 111.
[5] C. Favaretto et al., EJNMMI Radiopharm Chem. 6 (2021) 37.
[6] R.N. Wolf et al., Int. J. Mass Spec. 349-350 (2013) 123.
[7] S. Kreim et al., Nucl. Instrum. Meth. B 317 (2013) 492.

Speaker: Ulli Köster
• 61
Production of innovative radioisotopes for medical applications at the CERN-MEDICIS facility

Since its commissioning in December 2017, the CERN-MEDICIS facility has been providing non-conventional radioisotopes for research in nuclear medicine. Benefiting from decades of experience in the production of radioactive ion beams and in the mass separation process from the ISOLDE facility at CERN, CERN-MEDICIS quickly became a worldwide key player on the supply of of novel medical isotopes dedicated to research in the fields of cancer imaging, diagnostics, and radiation therapy.
The isotope production is performed using a target either placed in the radiation field generated from the 1.4 GeV proton beam delivered by the CERN Proton Synchrotron Booster scattered from the ISOLDE target, or using radioactive sources provided by one of the MEDICIS collaborating facilities. This later mode of operation allows CERN-MEDICIS to be among the only facilities running during CERN’s long shutdowns. Following laser and/or surface ionization, acceleration/extraction and mass separation, the isotope of interest is implanted on metallic foils. The resulting high molar (specific) activity product undergoes a radiochemistry purification process and is finally shipped to one of the medical laboratories from the MEDICIS collaboration (medicis.cern).
After a few years of operation, collections have been performed on a large panel of radionuclides such as $^{128}$Ba $^{149}$,$^{152}$,$^{155}$Tb, $^{153}$Sm, $^{167}$Tm, $^{169}$Er, $^{175}$Yb, $^{191}$Pt, and $^{255}$Ac. A couple of milestones have been achieved on the output of the facility, such as the collection of 500MBq of $^{175}$Yb, and a total separation efficiency of 50% reached in 2020 for $^{167}$Tm. These collections led to notable recent successes such as in-vivo and first proof-of-concept preclinical results in targeted radionuclide therapy obtained for high molar activity $^{175}$Yb and $^{153}$Sm products.
Constant developments are ongoing, such as innovative targets designs, in-target molecular formation to improve the release of specific isotopes, laser development in the dedicated MELISSA laboratory, study of new implantation materials, and post-collection radiochemistry.
Finally, CERN-MEDICIS is at the heart of the European medical isotope programme PRISMAP, which consists in a 23 institutes consortium, aiming at accelerating the research in nuclear medicine by providing a single hub for the medical community supplied with innovative radionuclides with high purity grade (prismap.eu, H2020 grand #101008571).

Speaker: Cyril Bernerd (KU Leuven - CERN)